Leather sander



Nov. 18, 1958 R. F. PENDERGAST 2,860,454

LEATHER SANDER Filed Oct. 3, 1955 4 Sheets-Sheet 1 Nov. 1 8, 1958 R. F. PENDERGAST LEATHER SANDER 4 Sheets-Sheet 2 Filed Oct. 3, 1955 Nov. 18, 1958 R. F. PENDERGAST 2,850,454

- LEATHER SANDER Filed Oct. 5, 1955 4 Sheets-Sheet 3 I waltz? I 100 a i/lwzzm/zf/elgym Nov. 18, 1958 R. F. PENDERGAST 2,850,454

LEATHER SANDER Filed Oct. 3, 1955 4 Sheets-Sheet 4 gym/fi /e United States Patent LEATHER SANDER Raymond F. Pendergast, Robinsdale, Minn.

Application (lctober 3, 1955, Serial No. 538,110

19 Claims. (Cl. 51139) This invention relates to a spreading and feeding assembly for flexible sheet material and to this assembly in combination with a leather sander.

As received from the basic hide processors, i. e., meat packers, etc., hides have the general skin shape of a main body portion, a neck, two fore legs and two hind legs. Their thickness is not constant and there are folds at the juncture of the legs and the main body. One major finishing operation is performed by sanding machines. These'consist of a feed roll against which operates a sand roller or belt, the latter proceeding at a higher speed than the feed roll. Both turn away from the feed side of the bite between the rolls, The hide emerges from the rolls with the sanded side of a fairly uniform texture and of a substantially constant thickness. In the preparation of hides for gloves, such as chamois, suede, kid, pigskin and the like, sand grain sizes of 120-240 are used.

Referring to Figure 1, applicant has sketched roughly a skin in plan view. When this skin is inserted between the sanding and feed rolls, an operator must keep spreading the skin with his fingers and hands in the direction of the two arrows in order to prevent a wrinkled portion from entering the rolls. Sometimes, he must hold back against the pull of the feed roller. 7 Thus, the line 11 in Figure 1 indicates a fold. This fold is shown in enlarged cross section in Figure 2. If the fold is down as shown in Figure 2 with the sanding belt below, that portion of the fold below the dotted line 12 will be cut olf by the sanding belt and for all practical purposes the arm 13 of the skin 10 in Figure 1 will be severed from the body. This type of damage can be avoided by a careful operator. The work is strenuous because it requires strength and constant attention. The hides cannot be fed through the machine at nearly the capacity of the machine to take them.

Returning to Figure 1, there are folds at the crotches of the side as at 14 and 18 which are diflicult for an operator to spead apart. These derive from the way the skin is folded under the leg pits of the animal. Despite great care, an operator has difiiculty in removing these folds and consequently not only is a cut-out portion as indicated by the dotted line 18 of not infrequent occurrence, but sometimes the feeding itself extends the fold, for example, along the dot-dash line 20 into the main body of the hide. This is due to the action of the pressure and sanding rolls at a point on the hide so close to the bite of these rolls that human hands, held away from the bite by a guard, cannot eliminate the fold.

The general object of this invention is to provide an automatic spreader for feeding the hide into the bite be tween the pressure and sanding rolls. A feature of this invention is the use of spreading fingers in conjunction with feed belts and a pressure plate which successively pull the leather outwardly in both directions from a center medran line and hold it there until a moment before ice the leather actually enters the bite between the pressure and sanding rolls.

Another object of this invention is to maintain the spread condition of the hide into the operating bite of the feed and sanding rolls. As will become clear in the disclosure that follows, applicant uses rubber fingers to do the spreading, and these fingers function because they are bent over from an erect position to a flattened position adjacent their base while engaging the hide. The amount of spreading that each finger can do is, therefore, dependent upon its length. It follows that the fingers cannot work into the bite of the rolls as closely as desired. Consequently, after the spreading of the side, the folds could re-form if not restrained. A feature of this invention is the provision of abrasive-surfaced belts which engage the hides at the moment that they are spread laterally a maximum distance and press them against the feed roll so that folds cannot re-develop, and these belts then carry the hide thus stretched deep into the bite of the feed and sanding rolls.

An object ancillary to the last object is to control the speed of the hide through the sanding zone in accordance with the rate of movement of the belt. Unless this end is accomplished, the hide will not have a constant thickness after processing nor a surface of uniform texture because the sanding belt, which is moving in the same direction through the bite as the feed belt, is moving at many times the linear speed of the feed belt. Even though the hide is held back by rolls through which it is passing on the feed side, which rolls are positively entrained with the .feed roll, irregularities seem to develop, and of course the end of the hide is snapped through and likely to be wasted. A feature of this invention is the pressing of the abrasive-surfaced tapes on the feed roll for a substantial distance immediately in front of the bite. As will appear, this involves the shortening of the shoe used for the spreading. Additionally, each tape is operated over freely movable sheaves so that the tapes are moving at the exact speed of the roll immediately in advance of the sanding bite.

Another object of this invention is to provide means for spreading the hide throughout its entire width. A feature of the invention is the provision of what is herein called elastic star wheels in which the peaks constitute the spreading fingers. fingers and when viewed transversely, the fingers are staggered 30-45 apart. The fingers on one side of the machine are slanted toward that side of the machine, and the fingers on the other side are slanted toward the other, and the effect of the staggering is to enable one finger to start to spread a fold by pushing material outwardly toward the next set of fingers, which in turn push the material still farther out.

Another object of the invention is to obtain a firm grip on the hide before the spreading fingers commence to operate. A feature of the invention is the use of the same abrasive-surfaced belts to lead a hide against the leading portion of the shoe, immediately in advance of engagement by the fingers. Unless this is done, the high projecting fingers are themselves likely to initiate a fold,

due to the action of gravity, particularly in the case of light hides.

These and such other objects as may hereinafter appear are attained in the embodiment of the invention which is shown in the accompanying drawings, wherein:

Figure l is a sketch of a plan view of an animal hide;

Figure 2 is a view taken on the line 22 of Figure 1;

Figure 3 is a schematic perspective of applicants leather sanding machine showing the general arrangement of parts;

Figure 4 is an end view showing the drive connections;

Each star wheel has four or six Figure 5 is a view taken on the line 5--5 of Figure 3;

Figure 6 is an enlargement of a portion of Figure 5;

Figures 7, 8 and 9 are views taken on the lines 7- -7, 8-8 and,9-9 of Figure 6 respectively;

Figure 10 is a view taken on the line 1010 of Figure 5; and- Figure 11 is a view taken on the line 11-11 of Figure 6 which line commences with the cylindrical surface through which the fingers project and extends to a point where the abrasive belts engage this cylindrical surface, and thereafter follows the under side of said belts to the point of disengagement with the feed roll. The scale of Figure 11 is the same as that for Figure 10 and slightly more than one-half that of Figure 6.

Continuing to refer to the drawings, and particularly to Figure 3, a rectangular frame 30'supports an idler roll 32 and a main drive roll 34 over which is entrained a sanding belt 36. The ends of the shaft carrying the idler roll 32 may be adjusted vertically so as to cant the roll with respect to the drive roll 34 and thereby assist in centering the sanding belt 36. This tilting means is controlled by a manually operable wheel 38. Additionally, to counteract a tendency to move laterally of the idler and drive rolls due to the action of the work, the machine will be'equipped with the centering pulleys shown in applicants copending application Serial No. 481,808, filed January 14, 1955, now Patent No. 2,813,382, dated November 19, 1957.

Mounted between supports 40 and 42 which are fastened to the frame is a pressure roll 44. Also mounted on these supports, but above the pressure roll, is a cleaning roll 46. Referring to Figure 4, a motor 48 through a belt drive 50 turns the shaft 52 upon which is mounted the main sanding drive drum 34. A second belt 54 drives a shaft 56 which through a sprocket not shown drives a chain 58 entrained over a sprocket 60 mounted on the shaft 62 which carries the pressure roll 44. The drive roll 34'is turning clockwise as indicated by the arrow 64 in Figure 4, and the pressure roll 44 is turning counterclockwise as indicated by the arrow 66. At the feed bite between the rolls, therefore, they are moving in the same direction. However, the surface of the drive roll and hence of the sanding belt is moving at a linear speed of about 4500 linear feet a minute, whereas the linear speed of the pressure roll which is commonly called the feed roll is four linear feet a minute.

Referring now to Figure 3, mounted on the feed side of the upper portion of the frame 30 at opposite sides thereof are two vertically positioned plates 68 and 70.

Mounted between these plates are four shafts 72, 73, 74

and 76. The shafts 72 and 76 are freely rotatable, being journaled at each end in bearing mounted on the plates 68 and 70. The shaft 74 is driven, referring to Figure 3, by means not shown at a speed such that fingers 82, referring to Figure 5, in maximum compressed engagement with a leather hide will be moving at approximately the same linear speed as the surface of the feed roll 44.

Mounted on the shaft 74 are spaced rubber star wheels 84, 86, etc., each of which have four outwardly directed fingers spaced 90 apart. Each star wheel is made of flat rubber sheeting and is squeezed between two metallic disks 88 and 90, one of which has a convex conical portion 92, and the other has a concave conical portion 94, so that the fingers such as 96 and 98 are canted with respect to the shaft 74. These disks 88 and 90 are keyed to the shaft 74.

Referring to Figure 10, intermediate each set of disks and mounted on the shaft 73 are freely rotatable pulleys such as 100 and 101 in transverse alignment respectively with pulleys 100. Entrained over pulleys 100 and 101 and over the freely rotating shafts 72, 73 and 76 is a narrow belt such as 102. This belt has an abrasive grain surface.

Positioned between the two end plates 68 and 70 is a curved plate 104, called herein the stretching shoe. ReferringtoFigure 6, the feed edge 106 of the stretching shoe is spaced from the shaft 74 so that the fingers 96 pass just beneath it. This plate steadily approaches the surface through which the fingers 96 project so that at the point 107, the plate will bend over the fingers so that they are substantially flat. The plate terminates adjacent the rubber surface of the feed roll 44.

Referring to Figure 6, the shaft 76 is located deep in the bite between the feed roll 44 and the sanding belt 36 so that the abrasive surface belts or tapes 102 engage the surface of the feed roll 44 between the points 108 and 110. The belts 102 are entrained over freely rotating members, namely the shafts 78 and 76, and the pulleys 100. They, therefore, move at the surface speed of the feed roll 44 either because of their direct engagement with the surface feed roll 44 or through a leather hide which is passing between the two.

The emery surface on the feed belts and its comparatively'long contact with the rubber surface of the feed is the means for keeping the speed of a hide down to the speed of the feed roll 44. At the bite 112 between the feed roll 44 and the sanding belt 36, unless something were holding the hide back, there would be a tendency of the hide to move through the bite at a speed which was a compromise between the speeds of the feed roll 44 and that of the sanding belt 36. The pressure roll, however, has a purchase on the belt between the points 111 and 110, and this provides sufiicient purchase to prevent the sanding belt 36 from pulling through the hide at the sanding belts surface speed.

Adjacent star wheels are 30 out of phase as shown by the disks 86, 114 and 116, and-by fingers 98, 99 and 122 in Figure 6.

Referring to Figure 5, the ends of the shaft 72 are mounted on arms such as 124, which are pivoted on bolts such as 126 mounted through the plates 68 and 70. These arms may be moved by screws 103 and so as to move shaft 72 and tighten or loosen the belts.

The operation of this feed mechanism will be explained while referring to Figures 6 and 11. Figure 11 is a view taken on the line 11-11, which commences above the surface of the cylinder through which project the fingers, to the line where the tapes engage the feed roll, and for a short distance beyond. The transverse line on the hide 132 along which the hide first engages the fingers, namely at 134, is called the line of initial finger contact. The transverse line at which the hide is brought into firm engagement with the abrasive surface of the tapes, namely at 136 in Figure 6, is called the line of tape contact. The line of tape contact is for all practical purposes the line atdwhich the fingers cease to exert lateral pressure on the hi e.

Referring now to Figure 11, the line of finger contact bears the numeral 134. The fingers 98 and 96 have just engaged the hide 10. This hide has a lengthwise, downwardly extending fold 138, see also Figure 7, which happens to lie between the two center finger-carrying disks 84 and 86, see Figure 10. Returning to Figure 6, the finger 99 has been bent over slightly thereby pushing the hide outwardly and the finger 122 is almost fully bent over. The finger 144 has commenced to spring back and the line of initial tape contact 134 is immediately after full depression of the finger 144.

Considering the action, and referring to Figure 11, the finger 144 initially was at the position of the finger 96. Its tip, shown in dotted outline on fingers 96, engaged the hide 10 which was moved outwardly along the dotdash line 97, assuming no slippage. The finger 86 was functioning similarly but in the opposite direction, see Figure 10. Returning to Figure 11, in moving outwardly, the fingers spread the fold 138 first to the configuration 148, see Figure 8, and then eliminated it, see Figure 9. Immediately after the hide had been fiattended, the tapes 150, 151 and 153 were brought into engagement therewith and pressed the flattened portion of the hide along the line 108 against the feed or pressure roll 44, see Figure 6.

This same process was duplicated with other fingers. Thus, the fingers 96 when at the point 152 was commenclng to form a small foid 154 in the hide because it was pushing out the fold 133. But the next finger 156, pushed the hide farther outward, thereby eliminating the fold 154. a

The action, therefore, is one of spreading the hide apart laterally and then at the moment when the spreading action has ended, gripping the hide with the abrasive surfaces of the spaced tapes or belts and holding the hide spaced. The tapes are following around the outer periphery of the roll 44 so that for a substantial distance the hide is held on both sides until it reaches the line 110.

As for.what happens to the folds in the short distance between the line 110 and the bite of the feed roll 44 and the sand belt 36, on the initial feed, the high speed of the abrasive surface of the belt 36 draws a blast of air into the bite which blows the leading edge of the hide into the bite. Once in the bite, the high speed of the sanding belt draws the hide tight between the tapes and the bite. This longitudinal tightness holds the hide in substantially the laterally stretched position that it possesses as it leaves the tapes along the line 110.

The applicant has shown four fingers on each star wheel. The number of fingers used depends in part upon the type of hide which is being processed. Fingers 60 apart have been tried. As shown in Figure 10, the fingers are 30 out of axial alignment so that a finger engages .the hide in a line at right angles to the sanding belt once for every 90 of rotation of the finger-carrying shaft 74. Whether a disk has six fingers or four fingers is somewhat immaterial because the spreading action depends upon the longitudinal spacing of the points at which the fingers engage the hide and a selected distance can be attained by varying either the number of fingers or the diameter of the finger-carrying shaft.

In the present design, the hide feed line 158, see Figure 6, is formed between the tapes and the leading edge of the shoe 106. On many early models, the shaft 160 over which the tapes are entrained was not employed. The tapes were simply fed directly over the pulleys. The present design gives a preferred feed of the hide to the fingers at the line of initial finger contact 134.

In the claims that follow the shoe 104 is called a plate or a spreading plate and is said to possess a delivery edge which is the edge 111 adjacent to the feed roll 44, in Fig. 6, and a feed edge which either may be at the point 134 or at 106. The important part of the shoe is shown as a segment of a cylinder but it could be variously shaped so long as the fingers first engaged the shoe in an erect position and were then bent over so as to spread the work. The fingers such as 98 and 99 may be referred to as peaks of a star wheel.

Having thus described his invention, applicant claims:

1. A spreading and feeding assembly for flexible sheet material comprising a frame, two rolls forming a bite mounted on said frame, a spreading plate having a delivery edge positioned adjacent one roll, a shaft positioned between said .edge and the bite of the rolls and parallel to their axes, a second shaft parallel to the first mounted on the frame, and a plurality of belts entrained over said shafts, said shafts being so related that the belts pass close to the edge of the plate and engage a substantial portion of the convex surface of the adjacent roll.

2. The spreading and feeding assembly of claim 1 wherein the first shaft has a small diameter and is deep in the bite between the rolls and the belts engage the surface of the roll moving away from the edge of the plate for several degrees of arc.

3. The spreading and feeding assembly of claim 1 wherein that surface of the belts engaging the roll carries abrasive grain.

4. A spreading and feeding assembly for flexible sheet material comprising a frame, two moving members having converging surfaces which form a bite mounted on said frame, a plate having a feed edge and a delivery edge generally parallel to the bite and connected by a surface generated by a line parallel to the bite and moving at right angles thereto, the delivery edge being immediately adjacent one of said converging surfaces, a plurality of fingers engageable with said surface, means for moving the fingers towards the delivery edge and means for moving the fingers laterally while pressing against the surface.

5. A spreading and feeding assembly for flexible sheet material comprising a frame, two moving members having converging surfaces which form a bite mounted on said frame, a plate having a feed edge and a delivery edge generally parallel to the bite and connected by a surface generated by a line parallel to the bite and moving at right angles thereo, the delivery edge being immediately adjacent one of said converging surfaces, a plurality of fingers engageable with said surface, means for moving the fingers towards the delivery edge, and means for moving selected fingers laterally in one direction and other fingers laterally in the other direction.

6. A spreading and feeding assembly for flexible sheet material comprising a frame, two moving members having converging surfaces which form a bite mounted on said frame, a plate having a feed edge and a delivery edge generally parallel to the bite and connected by a concave surface generated by a line parallel to the bite and moving at right angles thereto, the delivery edge being immediately adjacent one of said converging surfaces, a shaft positioned within the concave face of the plate parallel to the plate and closer to the delivery edge than to the feed edge, and a plurality of equal length elastic fingers radiating from said shaft and canted from a plane at right angles to the axis of the shaft, the length of the fingers being such that their tips will just engage the surface near the feed edge and will be pressed over as the shaft is turned toward the delivery edge.

7. The spreading and feeding assembly of claim 6 wherein the fingers are groups of peaks on spaced star wheels mounted on the shaft.

8. The spreading and feeding assembly of claim 6 wherein the fingers are groups of peaks on spaced star wheels mounted on the shaft and wherein all of the peaks on the star wheels on one side of a selected point on the shaft are canted away from that point toward one side of the assembly and all of the peaks on the star wheels on the other side of the point are canted in the opposite direction.

9. The spreading and feeding assembly of claim 8 wherein the peaks of a star wheel are staggered when viewed endwise with the peaks of the next adjacent star wheel.

10. A spreading and feeding assembly for flexible sheet material comprising a frame, a pair of moving converging rolls forming a bite mounted on the frame, a plate having a smooth surface mounted on the frame with a straight edge spaced from the bite but immediately adjacent the surface of one of the converging rolls, automatic means for spreading the sheet material on the smooth surface of the plate and pushing it toward said edge, and a means for holding the material stretched as it leaves the edges and for pressing it against the roll as it moves into the bite.

11. A spreading and feeding assembly for flexible sheet material comprising a frame, a pair of moving converging rolls forming a bite mounted on the frame, a plate having a smooth surface mounted on the frame with a straight edge spaced from the bite but immediately adjacent the surface of one of the converging rolls, automatic means for spreading the sheet material on the smooth surface of the plate, and pushing it toward said edge, and a plurality of belts adapted to engage the stretched material near said edge and press it against the feed roll as it moves into the bite.

12. A spreading and feeding assembly for flexible-sheet material comprising a frame, two rolls forming a bite mounted on said frame, a spreading plate having a delivery edge positioned adjacent to one roll and a surface curving away from said edge parallel to the roll axes toward a feed edge, and a shaft parallel to the roll axes positioned within the curved plate, and closer to said departure edge than to the feed edge, a. plurality of elastic fingers radiating from said shaft, some canted laterally in one direction and some in the other, a second shaft near the bite of the two rolls, and a plurality of belts entrained over the two shafts and between the fingers of the first shaft.

13. A sanding machine comprisinga feed roll and a pressure roll with a straight line bite therebetween, an abrasive element on the surface of the pressure roll at the bite, means for rotating the pressure roll at a higher speed than the feed roll, a shoe having a feed edge and a delivery edge parallel to each other and to the bite, the delivery edge being immediately adjacent one of said converging surfaces, a shaft positioned parallel to the bite with its axes approximately 90 around the feed ro-ll from the bite and closer to the delivery edge of the shoe than to the feed edge, a plurality of equal length elastic fingers projecting radially fromsaid shaft, the tips of the fingers adapted to engage the shoe near the feed edge and to be bent over nearthe delivery edge, and means for rotating said shaft.

14. A sanding machine comprising a frame, a feed roll and a pressure roll mounted on said frame parallel to each other so as to form a bite, an abrasive element on the surface of the pressure roll at the bite, a shaft mounted on the frame parallel and adjacent to the feed'roll and spaced arcuately from the bite between .the feed and pressure rolls, a plurality of elastic. star wheels mounted on and keyed to the shaft, a freely rotatable pulley mounted on the shaft between selected star wheels, means for rotating the star wheel shaft so that the median point of the fingers moves at approximately the same linear speed as that of the surface of the feed roll, a shaft of comparatively small diameter positioned close to the bite of the feed and pressure rolls, a forward shaft positioned parallel to the star wheel shaft on the side away from the feed roll, a belt entrained over each pulley and over both the small and the forward shafts, the points of all star wheels on one side of a plane normal to and through all the shafts being canted toward that side of the frame and the points of the star wheels on the other side of the frame being canted in the opposite direction, and a shoe having a curved cross section ex tending from a feed edge to a delivery edge parallel to the shafts, the delivery edge being adjacent a surface of the feed roll and closer to the star wheel axes so as to bend over the points of the star wheel.

15. A spreading and feed assembly comprising a frame, a shaft mountedv on the frame, a plate having a smooth surface facing the shaft and having a straight delivery edge parallel to the shaft mounted on the frame, and means on the shaft engageable with the smooth surface of the plate for spreading toward opposite ends of the plate a piece of flexible sheet material passed between the shaft and the plate.

16. A spreading and feed assembly comprising a frame,

a shaft mounted on the frame, a plate having a smooth surface facing the shaft and having a straight delivery edge parallel to the shaft mounted on the frame, bendable fingers radially projecting from the shaft, said fingers having a radius greater than the distance of the shaft from the delivery edge of the plate, and the fingers along one end of the'shaft being canted toward that end and those along the other end ofthe shaft being canted toward the latter end.

17. The spreading and feed assembly of claim 15 wherein the smooth surface of the plate is generated by a line parallel to the shaft and moving more closely thereto as it approaches the straight edge.

18. The spreading and feed assembly of claim 15 and means independently operable with respect to the shaft and engageable with the work near the delivery edge of the plate for holding the work spread as it leaves the edge of the plate.

19. The spreading and feed assembly of claim 15 and a plurality ofspaced belts having one fiight positioned between the shaft and the plate and all belts engageable with the work near the delivery edge of the plate for holding the work spread as it leaves the delivery edge.

References Cited in the file of this patent UNITED STATES PATENTS 

